Conventional acoustic pianos such as grand pianos and upright pianos are made up by many components. Since assembling these components is very complex, the assembling operation takes long time. In particular, since an action mechanism provided correspondingly to each key requires many components, its assembling operation is very complex.
For example, in an action mechanism described in Japanese Unexamined Patent Application Publication No. 2005-292361, a plurality of components act each other, and key operation by key pressing and key releasing is transmitted to a hammer. In particular, a support assembly configuring part of the action mechanism operates with various components assembled together. The support assembly has not only a mechanism which achieves string hammering by the hammer in accordance with key pressing but also an escapement mechanism for releasing a force transmitted to the hammer by key operation immediately before string hammering. This mechanism is an important mechanism for achieving basic operation of the acoustic piano. In particular, in a grand piano, a double escapement mechanism having a repetition lever and a jack combined together is generally adopted.
The operation of the action mechanism provides a sense (hereinafter referred to as a touch feeling) to a finger of a player through a key. In particular, the structure of the support assembly provides an important influence on the touch feeling. For example, the touch feeling by the operation of the escapement mechanism is called let-off.